In this article, we present a novel analytical approach used to derive a new multiscenario line-of-sight (LOS) probability model for cellular network deployments in the U.K. The approach considers the use of lamp post databases as statistically representative geospatial data points for the evaluation of LOS likelihood from macrocellular base stations. Crucially, the proposed model is built on a high-resolution (0.25-1 m) 3-D digital surface model underpinned by real network and environmental datasets and validated with supporting field measurements. This work unifies all common cell site classification types: urban, suburban, and rural into a single 3-D LOS statistical probability model while also addressing the influence of endpoint height properties up to 10 m. The contributions outlined in this article have applications in statistical path loss modeling and coverage/outage probability. They also have direct application in deployment modeling of millimeter-wave (mmWave) mobile access networks (24.25-52.6 GHz) and wireless x-haul transport networks (71-174.8 GHz).